The present disclosure relates to a cable connection structure, an imaging apparatus, and an endoscope in which coaxial cables and a circuit board are connected.
In the past, an endoscope that is inserted into a subject and observes a subject region has been known and widely used in a medical field or the like. The endoscope is configured such that an imaging module, on which an electronic component, such as an image sensor, is mounted, is provided inside a tip portion of a flexible elongated insertion tool. There is a demand to reduce a diameter and a length of the tip portion of the insertion tool in consideration of ease of introduction to a patient.
In relation to the demand as described above, a known cable connection structure is known in which a core wire of a coaxial cable is connected to a connection electrode provided on a second flat portion or a stepped surface in a circuit board that includes, on a principal surface side, a first flat portion having a flat plate shape, the second flat portion being a plate thinner than the first flat portion, and the stepped surface being an inclined surface or a vertical surface provided at a boundary between the first flat portion and the second flat portion (for example, see Japanese Patent Publication No. 5631618 (referred to as JP5631618).
In JP5631618, it is possible to reduce a mounting height of the coaxial cable, that is, it is possible to reduce a diameter, when used in an imaging apparatus, an endoscope, and the like; however, connection of a plurality of coaxial cables is not taken into account. When a plurality of coaxial cables are connected to a circuit board, positions of the coaxial cables with respect to the circuit board are determined while the coaxial cables are held by a tool or the like, but it is difficult to determine the positions of the plurality of thin coaxial cables with accuracy, and connection operation needs skill. Further, if the positioning accuracy is low, connection strength and reliability are reduced.
As a technology for improving the positioning accuracy of cables, a technology has been disclosed, in which, in an imaging module in which a plurality of core wires of a flexible multi-core cable are connected to an image sensor via a circuit board, a recessed portion is provided on a longitudinal side surface of the circuit board that is provided parallel to an image sensor, and the core wires are housed and connected in the recessed portion in order to prevent the core wires from being spread out and reduce a diameter of the imaging module (for example, see Japanese Laid-open Patent Publication 2009-27709).